Three-dimensional (3-D) object sensing is required in a variety of industrial and scientific applications such as thermal sensing, animation, laser machining, parts inspection, virtual reality, building scanning, and architecture and model construction. Target 3-D information is generally acquired by scanning a laser beam in transverse dimensions of a target to acquire the target transverse and axial (in light direction) dimensions data. As described in the prior art, much effort is spent to extract the target axial direction data such as via optical triangulation methods.
More commonly, time of flight laser radar methods using time/frequency RF modulation of the laser beam have also been used for 3-D object distance measurements. Object transverse dimensions data is simply acquired by scanning the laser beam across the lateral dimensions of the target on a point-by-point basis with a fixed transverse scan point count, e.g., 500×500 points for all the different axial planes of the object determined by other distance sensing methods such as laser radar or triangulation. For example, triangulation has also been used to measure object lateral displacement.
Other prior art works in distance measurement sensors include various methods such as absolute distance measurement with heterodyne optical feedback on a Yb:Er glass laser; absolute Distance Measurement with an Optical Feedback Interferometer; absolute distance measurement by dispersive interferometry using a femtosecond pulse laser; long distance measurement with high spatial resolution by optical frequency domain reflectometry using a frequency shifted feedback fiber laser; distance measurement with extended range using lateral shearing interferometry and Fourier transform fringe analysis; 2π ambiguity-free optical distance measurement with subnanometer precision with a novel phase-crossing low-coherence interferometer; high-accuracy absolute distance measurement using frequency comb referenced multiwavelength source; absolute distance measurement by lateral shearing interferometry of point-diffracted spherical waves; adaptive whole-field optical profilometry: a study of the systematic errors; PIN-diode based optical distance measurement sensor for low optical power active illumination; and distance measurement system with a planar light wave circuit.
Known U.S. patents include U.S. Pat. No. 6,753,950 issued to John Morcom, entitled “Optical Distance Measurement”; U.S. Pat. No. 6,829,043 issued to R. Lewis, C. Thomson, titled “Distance measurement device with short distance optics”; L. A. Campbell, Ultrasonic distance measurement system, U.S. Pat. No. 7,388,810 issued Jun. 17, 2008; M. Kloza, Device for precise distance measurement, U.S. Pat. No. 7,359,039 issued Apr. 15, 2008 which describes an RF delay method.
Other U.S. patents include U.S. Pat. No. 7,324,218 issued Jan. 29, 2008 to J. Stierle, P. Wolf, G. Flinspach titled “Method and device for distance measurement”, which describes an optical method; U.S. Pat. No. 7,315,355 issued Jan. 1, 2008 to P. Sperber tided “Method and device for optical distance measurement”; M. Moriya, S. Ishii; U.S. Pat. No. 7,233,279 issued Jun. 19, 2007 to Satoshi, T. Seld, K. Hamada, K. Oka, A. Ohta, titled “Method and device for distance measurement by pulse radar” which describes RF Radar; U.S. Pat. No. 7,221,435 issued May 22, 2007 to J. Stierle, P. Wolf, K. Renz, titled “Device and method for optical distance measurement”; T. Gogolla, A. Winter, H. Seifert, Method of and apparatus for electro-optical distance measurement, U.S. Pat. No. 6,917,415, Jul. 12, 2005; A. J. Barker, Optical sensor for distance measurement, U.S. Pat. No. 6,876,441, Apr. 5, 2005; D. Schmidt; J. Stierle, P. Wolf, G. Flinspach, Device for optical distance measurement of distance over a large measuring range.
Other U.S. patents include U.S. Pat. No. 6,833,909, Dec. 21, 2004; W. Holm; R. H. Hines, Apparatus for producing a light beam having a uniform phase front and distance measuring apparatus, U.S. Pat. No. 4,105,332, Aug. 8, 1978; L. J. Lego, Jr., High pulse repetition frequency electro-optical viewing system, U.S. patent No. issued on Sep. 2, 1975; D. C. Shafer, A. G. Butler; W. R. Burnett, Level with angle and distance measurement apparatus, U.S. Pat. No. 6,741,343 issued on May 25, 2004.
Publications and patents authored by or issued to Nabeel A. Riza, a co-inventor of the subject application include N. A. Riza, “Multiplexed Optical Scanner Technology,” U.S. Pat. No. 6,687,036, Feb. 3, 2004; N. A. Riza and A. Bokhari, “Agile Optical Confocal Microscopy Instrument Architectures For High Flexibility Imaging,” in Three Dimensional Confocal Microscopies, BIOS 2004 Biomedical Optics, Photonics West, Proc. SPIE Vol. 5324, Paper No. 14, pp. 77-88, San Jose, Calif., January 2004; S. A. Khan and N. A. Riza, “Demonstration of a No-Moving-Parts Axial Scanning Confocal Microscope thing Liquid Crystal Optics,” Opt. Comm., Vol. 265, pp. 461-467, 2006; M. Sheikh and N. A. Riza, “Blood Vessel 3-D Imaging Using Electronically Controlled Optics Lens-Based Confocal Microscopy,” OSA Top. Mtg on Biomedical Optics, Technical Digest, paper no. BTuF64, March 2008; N. A. Riza, M. Sheikh, G. Webb-Wood, and P. G. Kik, “Demonstration of three-dimensional optical imaging using a confocal microscope based on a liquid-crystal electronic lens,” Optical Engineering Journal, Vol. 47, No. 6, pp. 063201-1 to 063201-9, June 2008.
Ideally, one would like to have a relative distance sensor that non-invasively acquires 3-D object reconstruction data from an illuminated target with minimal object (or laser beam) scanning and minimal volumetric data generation. Recently, N. A. Riza, a co-inventor of the subject application filed a related U.S. Provisional Application No. 61/097,589, filed on Sep. 17, 2008 titled “Hybrid Design High Dynamic Range High Resolution Optical Distance Sensor” and N. A. Riza and authored an article S. A. Reza, “Non-Contact Distance Sensor using Spatial Signal Processing,” Optics Letters, Vol. 34, No. 4, pp. 434-436, Feb. 15, 2009 which proposed and demonstrated an optical distance sensor using direct spatial processing (basic version does not use time/frequency modulation of the light) that has a wide distance dynamic range, excellent on-axis distance measurement resolution, and high optimal spatial profiling resolution (i.e., transverse to optical beam propagation axis) at all axial distances of the 3-D scan operation.
The methods and devices of the present invention further expands on the proposed spatial processing distance sensor such that, it forms a spatially smart, optical sensor to engage a variety of spatial dimensions 3-D targets, such as needed for temperature sensing via an array of different size Silicon Carbide optical chips or a 3-D target with different size transverse structural zones at different axial depths.
Compared to prior-art optical distance measurement 3-D sensors where the scanning beam spot size stays fixed (apart from the natural beam diffraction-based expansion) for all 3-D scarf positions of the beam on the 3-D target (what is called non-smart spatial sampling), the optical sensor of the present invention adjusts the transverse beam spot size at each axial position based on the specific target's 3-D shape profile.
A problem with all prior-art laser scanning projection displays is that the farther the distance of the screen from the laser scan optics, the poorer the spatial resolution of the image due to the natural diffraction-based spreading of the Gaussian laser beam that forms the individual pixel/spot in the pixelated display.
What is needed to solve these problems is a laser scanning projection display that does not have a drastic reduction in display spatial resolution as the distance of display screen from laser optics increases. In addition, for any given screen distance, one would like to produce a display with an increased pixel count without sacrificing the pixel size. Proposed in this application is such a smart optical display that does away with the limitations associated with the classic laser scanning display approach.